Field of the Invention
The invention relates in general to elevator systems, and more specifically to new and improved methods and apparatus for determining load in an elevator car.
Description of the Prior Art
In the prior art, the load in an elevator car is usually determined by apparatus which detects the weight of the load in the car. For example, weight switches are installed at the bottom of the elevator car. Such switches, however, are subject to mechanical misadjustment, and when misadjusted, they give inaccurate readings. Such switches may also give inaccurate readings for other reasons as well, such as an uneven load distribution in the elevator car. Also, regardless of how accurate the indication of the load weight is, it may still give an inaccurate indication of how the space in the elevator car is occupied. For example, bundles, vehicles, wheelchairs, strollers, children, and the like, may consume considerable space without adding significantly to the weight of the car load. Thus, a downwardly traveling elevator car which should be by-passing down hall calls because there is no more room for passengers, may stop at every such call if the weight of the load is not sufficient to trigger by passing. A "next" car at the main floor which should be dispatched because it can accept no more passengers, may continue to wait for the normal time period, if the car weight is not sufficient to trigger immediate dispatching.